Try moving the playback window around, pausing, skipping through the video forwards and backwards, and switching to full screen mode and back (f key)

If you are not already using one (such as GNOME Shell), enable a compositing manager (like Compiz: menu -> System -> Preferences -> Desktop Effects, or run compiz-gtk) and repeat the video playback test

Expected Results

Both the gstreamer test video and the Totem video should play smoothly (watch the white noise in the gstreamer test video), in the correct colors

In the Totem video, pausing and skipping and switching to and from full screen should work with no delays and no kind of corruption to the video or the rest of the desktop